Adventures in Etymology: Oplosaurus, Mastodonsaurus

From: Ben Creisler bh480@scn.org
Adventures in Etymology: Oplosaurus, Mastodonsaurus
I recently had a chance to do some research at the
University of California library at Berkeley, and have
come back a bit humbled--a couple of old etymologies I
thought I had resolved in fact are much WEIRDER than I
could have guessed. I was consulted on both of these
etymologies for books or museum diplays, and worked with
the best info I had a hand--the Greek and Latin roots were
seemingly fine, but the REASON and meaning I proposed for
each name now appear to be off. The original publications
in each case are found in special or stored collections
that need to be consulted in person (no requests for
photocopies allowed!). The Berkeley palaeo library stuff
has been in major flux for a few years and somewhat
difficult to track down--the contents of the Earth
Sciences Library were transferred in part to the
Biosciences Library, the Main Library, special collections
and into storage when Paleontology became part of
Department of Integrative Biology rather than Earth
Sciences. Here are a few examples with quotations from the
original texts to spare others the trouble of tracking
them down:
Oplosaurus armatus a mosasaur!?
List-member Darren Naish asked me about this puzzler for
his excellent book Dinosaurs of the Isle of Wight, and I
provided my "educated" (now maybe debunked!) guess based
on what I could find at the University of Washington
Library. The name almost certainly comes from Greek hoplon
meaning "weapon, shield, arms, armor" (dropping the
initial Greek "h" is this case in not uncommon in
scientific names)--but why Gervais proposed such a name
for what is now known to be a sauropod tooth is a mystery
that turns out to be even weirder than Darren or I
suspected. The only material I had at hand before
checking sources at Berkeley was the original description
of the tooth and illustration of the tooth in an 1852
British journal, in which Mantell commented that the tooth
might come from an animal like Hylaeosaurus armatus. It
seemed plausible to me at the time that Gervais might have
assumed the tooth came from an armored animal similar to
Hylaeosaurus, which would explain his choice of the name
Oplosaurus armatus (note the same species name
meaning "armed"). WRONG! I checked on some of Gervais'
works available at Berkeley and it turns out he thought
the tooth he called Oplosaurus came from a MOSASAURID-
related reptile, not a dinosaur! He rejected Owen's
Dinosauria and used the Mosasauridae as a kind of catch-
all group to embrace a wide range of reptiles distinct
from the Megalosauridae and the Iguanodontidae (in which
he included Hylaeosaurus). Did Gervais think the tooth
came from a meat-eating animal, in which case Oplosaurus
might mean "weapon lizard" or maybe "armed lizard" for
its teeth? Frankly, the thick spoon-shaped tooth does not
look particularly "weapon-like" to me. The species
name "armatus" is Latin for "armed"--again, the tooth
doesn't seem like a weapon to be armed with! Maybe he
originally came up with the name based on Mantell's
comments about the armored Hylaeosaurus, retained the name
but then later changed his classification of the animal
before he went into print. Here's the description from
the second edition of his Zoologie et Paléontologie
françaises (1856), page 464.
OPLOSAURUS
"On peut en effet regarder comme indiquant un genre à part
de Mosasauridés, une dent singulière que M. Wright a
recueillie dans l'argile wéaldienne de Brighton-Bay, à
L'île de Wight, et dont il donné la figure et une courte
description dans les Annals and Mag. of nat. hist., pour
le mois d'août 1852. Cette dent, qu'il a bien voulu nous
montrer pour avoir notre avis sur l'animal dont elle
provient, est longue de 0,090, couronne et racine. Sa
partie coronale, plus large que la radiculaire, est
convexe d'un côté, subconvexe de l'autre; ses bords
antérieurs et posterieurs sont en carène, et il y a
l'indication d'une troisième carène verticale sur le
milieu de la face convexe; la racine est en partie
enveloppé de matière osseuse, montrant que son mode
d'implantation était le même que dan les Mosasaures et
Léiodons. On pourra donner à l'espèce type du genre
Oplosaurus le nom d'armatus."
[translated (over)literally:
"One can in effect regard as indicating a genus distinct
from the Mosasauridae a singular tooth that Mr. Wright
collected in the Wealden clay at Brighton Bay, Isle of
Wight, and for which he provided a figure and a short
description in the Annals and Magazine of Natural History
for the month of August 1852. This tooth, which he greatly
wished to show us to have our opinion on the animal to
which it belonged, is [85mm] long, crown and root. Its
crown, larger than the root, is convex on one side,
subconvex on the other; the front and back edges are
keeled, and there is an indication of a third vertical
keel on the middle of the convex face; the root is partly
covered in bony material, showing that its mode of
implantation was the same as in Mosasaurus and Leiodon.
One may give the type species for the genus Oplosaurus the
name 'armatus'."
****************
Mastodonsaurus "teat-like tooth lizard" (NOT "Mastodon
(size) lizard")
When the American Museum updated their displays, they
asked me about the meaning of Mastodonsaurus, a giant (20
ft) Triassic amphibian, and I suggested "Mastodon (size)
lizard" based on the confidently stated explanation given
by Charles Gilmore in 1944 in the Smithsonian Series vol.
8 (Fishes, Amphibians, Reptiles) (pg. 166): "In the year
1824 Professor Jaeger discovered in Wuerttemberg, Germany,
the fossil remains of an amphibian so large that he
applied to it the name Mastodonsaurus, not because it had
any relationship to the elephantlike mastodon--which is,
of course, a mammal--but in reference to its very great
size."
I found the same seemingly plausible etymology indicated
in some dictionaries (Mastodon + saurus), and had the
meaning further confirmed by a well-known and long
established vertebrate paleontologist with an interest in
nomenclature. Other sources gave a confusing array of less
obvious alternate meanings--in addition to the
literal "breast tooth lizard" (Greek mastos "breast,
nipple, dug"+ Greek odon "tooth") in some books, Agassiz
gave the derivation as "jaw tooth lizard" and Rainer
Schoch in his excellent recent monograph explained it
as "wart-toothed lizard." A few old German sources gave
the meaning as "zitze" tooth lizard, which can
mean "nipple" or "teat." Comparisons with a "breast"
or "nipple" did not make much sense to me based on the
long conical type tooth with a damaged tip. Owen, of
course, tried to change the name to Labyrinthodon because
he thought Mastodonsaurus was misleading for unavoidably
associating the tooth either with a Mastodon or with a
breast, and implying identification as a reptile rather
than an amphibian! There is no substitute for the original
description, however, and I was finally able to read
Jaeger's first description of the single holotype tooth in
the rare books collection at Berkeley. Note that the name
Mastodonsaurus was first proposed for a single very large
striated tusk-like tooth (still the largest amphibian
tooth known) without any associated bones--and Jaeger was
also the "perceptive" researcher who came up with the name
Phytosaurus "plant lizard" for a meat-eating archosaur!
Here's what Jaeger says in part in "Jaeger, G F. 1828.
Uber die fossile reptilien, welche in Wurtemberg
aufgefunden worden sind. Stuttgart, J.B. Metzler 48"
(pages 35-36):
MASTODONSAURUS
"Dieser Zahn is naemlich besonders ausgezeichnet durch
seine zitzenartige Spitze...der Zahn endigt sicht in eine
gewoelbte Spitze, die aber in ihrer Mitte eine
nabelfoerimige Vertiefung, und in der Mitte derselben
wieder eine kleine Erhoehung hat."
Which translates loosely as:
"This tooth is most particularly remarkable for its teat-
like tip...the tooth terminates in a domed tip, which has
in turn a navel-shaped depression in its center, and
furthermore a small knob in the center itself."
Maybe it did not occur to the good doctor Jaeger that the
tip was actually damaged, worn or broken, creating the
shape that apparently reminded him in some way of a
mammalian teat!
Jaeger later correctly associated the tooth with some
large bones from the back of a skull, which he had named
Salamandroides giganteus "gigantic salamandar-like one"
for their resemblance to bones of living salamanders.
Since the name Mastodonsaurus had priority by a couple of
pages in the original book, the official name became
Mastodonsaurus giganteus.
I guess I should contact the American Museum and ask them
to change their display. Kind of embarrassing...